The objective of this contract is to support the Developmental Therapeutics Program's (DTP) drug development effort and also perform critical activities for the Division of Cancer Treatment and Diagnosis (DCTD) in order to allow potential drug candidates proceed to clinical trials. Toxicology studies are conducted in intact, healthy, experimental animals as the final step in the preclinical drug development scheme. Histologic examination of lesions produced by the drug under evaluation is a crucial endpoint in the determination of a drug's safety and toxicity and in the reversibility of that toxicity. This contract supports the NCI in a variety of functions including, independent pathology assessment of toxicology studies (assures quality and consistency amongst the contract laboratories); histopathology support for studies as needed; repository storage of pathology materials and DTP documents; determination of tissue binding specificity of therapeutic antibodies; and performance of specialized histologic procedures such as immunohistochemistry.